The present invention is related generally to blow molded plastic containers for liquid, flowable, and squeezable products, and more particularly to stretch blow molded containers that may be suitable for use with food or beverage products packaged by traditional hot-fill processes.
Many food and beverage products are sold to the consuming public in plastic containers, such as those that are shown in U.S. Pat. No. 5,472,105 (Krishnakumar et al.), U.S. Pat. No. 5,704,503 (Krishnakumar et al.), and U.S. Pat. No. 5,971,184 (Krishnakumar et al.). The design of such containers must take into account the container's structural integrity, the manufacturing cost to mass-produce the container, and the aesthetic appearance of the container to the eye of the consumer.
Hot-fillable plastic beverage containers such as those disclosed in the above referenced patents must be structurally sound to withstand various forces relating to the so-called “hot-fill” process. In a hot fill process, a product is first added to the container at an elevated temperature (e.g., about 82° C.), which may be near the glass transition temperature of the plastic material. Then, the container is capped. As the capped container and its contents cool, the contents tend to contract leading to a volumetric change, which creates a partial vacuum within the container. In the absence of some means for accommodating these internal volumetric and barometric changes, containers tend to deform and/or collapse. For example, a round container may undergo ovalization, or tend to distort and become out of round. Containers of other shapes may become similarly distorted. In addition to these changes that adversely affect the appearance of the container, distortion or deformation may cause the container to lean or become unstable. This may be particularly true where deformation of the base region occurs.
Containers that store products under pressure, such as carbonated beverages, also experience pressure changes due to changes in ambient temperature. A commercially satisfactory container must not only withstand these forces from a structural viewpoint, but it must also present an aesthetically pleasing appearance to the ultimate consumer. Moreover, it must withstand rough handling during transportation to that consumer.
The price of many products sold to the consuming public is affected to an extent by the cost of packaging. With plastic beverage containers, the cost of manufacturing a container is affected by the cost of the plastic making up the container. Therefore, if the amount of plastic in a container can be reduced (i.e., through a process known as “light weighting”), the cost of manufacturing the container may be reduced commensurately. In achieving this goal, however, it is known that the thinner the walls and base of the container become, the greater the need is to utilize imaginative designs to provide a container that is commercially acceptable.
The desire to decrease the amount of plastic used in a container has resulted in the development of different techniques to design containers that have structural integrity with minimal use of plastic. It is known that the shape and location of structural elements such as ribs, hinges, panels, and the like may affect the container's overall structural integrity. While various structural elements molded in the side panel and base structure may afford structural integrity, they must also be visually appealing to the consumer.
The Krishnakumar et al. '105 patent noted above discloses a hot-fillable plastic container having a panel section with vacuum panels and an end grip, which panel section resists ovalization and other deformation during filling, product cooling, and handling. The container has a substantially cylindrical panel section, with a pair of vertically elongated vacuum panels disposed on opposing sides of a vertical plane passing through a vertical centerline of the container. Front and rear label attachment areas are provided between the vacuum panels. A pair of vertical ribs are disposed on either side of each vacuum panel which act as hinge points to maximize movement of a concave recess in the vacuum panel; the vertical ribs also resist longitudinal bending. The concave recess is formed at an initial inwardly-bowed position with respect to the panel circumference, and is movable outwardly to a second position within the panel circumference upon increased pressure during filling, and movable inwardly to a third position to accommodate the vacuum which forms during product cooling.
The Krishnakumar et al. '503 patent noted above discloses a panel design for a hot-fillable plastic container, which has a tall and slender panel section. The panel configuration provides increased resistance to longitudinal bending and hoop failure, yet provides good hoop flexibility to maximize vacuum panel movement. The panel section has a substantially cylindrical circumference with a plurality of vacuum panels symmetrically disposed about the panel circumference, post walls between the vacuum panels, and land areas above and below the vacuum panels. The ratio of vacuum panel height D to panel diameter C is on the order of 0.85 to 1.05. Longitudinal post ribs are provided in the post walls. The land areas above and below the vacuum panels are of a height E greater than on the order of 0.45 inch, and the ratio of the land area height E to panel diameter C is on the order of greater than 0.1. Circumferential hoop ribs are provided in the land areas to prevent ovalization and hoop collapse.
The Krishnakumar et al. '184 patent noted above discloses a hot-fillable plastic container having a panel section of a size suitable for gripping the container in one hand. The panel section includes two opposing vertically-elongated and radially-indented vacuum panels, and two opposing horizontally-disposed and radially-indented finger grips. Each vacuum panel preferably has an invertible central wall portion movable from a convex first position prior to hot-filling of the container, to a concave second position under vacuum pressure following hot-filling and sealing of the container.
Containers such as those disclosed in the above-referenced Krishnakumar et al. patents are typically formed with an even number—especially six—vacuum panels, which are symmetrically disposed about a longitudinal axis of the container. Other means for resisting ovalization and similar such deformation, which use an odd number of vacuum panels, are also known in the prior art. For example, Japanese Laid Open Utility Model Registration No. 56-658031 discloses a hot fill container, which has a base, a body, and a neck. The body includes a plurality of spaced-apart vertical lands and an odd number of spaced-apart panels. Finally, it discloses that a container having the odd number of panels may resist deformation forces caused by pressure reduction in the bottle because those panels are not disposed about the longitudinal axis of the container in a diametrically opposed relationship.
U.S. Pat. No. 6,044,996 (Carew et al.) also discloses a hot-fill container formed from a polymeric material comprising a base, a body, and a neck, wherein the body comprises an odd number of spaced-apart panels that are responsive to internal pressure changes in the container. According to the Carew et al. '996 patent, hot-fill bottles of a given capacity having an uneven number of deformable panels (e.g., five) of a given wall thickness unexpectedly accommodate significantly higher volume reductions before collapsing and distorting in an uncontrolled manner than known hot-fill bottles of the same capacity having an even number of panels (e.g., six) of the same wall thickness.
Notwithstanding the contributions of the foregoing prior art, neither an odd nor an even number of panels alone may satisfy the problems of ovalization and deformation, which may be faced by plastic beverage containers that also must present an aesthetically pleasing appearance to the ultimate consumer.
The Institute of Packaging Professionals (IoPP), for example, announced its 1999 AmeriStar award winners at the 1999 AmeriStar Package Awards during WestPack in November 1999. There were three award winners in the food category, including Graham Packaging's Tropicana Twister® (a registered trademark of Tropicana Products, Inc., 1001 13th Avenue, East Bradenton Fla. 33506 U.S.A.) plastic bottle design. The bottle won due to its distinctive shape, broad label panel and unique design that enhances shelf appeal and product quality.
The illustrated preferred embodiment of that bottle design included two generally parallel diagonal ribs 42, as well as an offset rib 43 having both a generally horizontal leg 44 and a diagonal leg 45 which is generally parallel to the diagonal ribs 42. These ribs minimized the need for special handling with respect to vacuum conditions for a hot-filled product. It did not, however, depend upon uniquely designed vacuum panels. See, e.g., U.S. Pat. No. 5,908,126 (Weick et al.) and U.S. Pat. No. Des. 415,964 (Manderfield, Jr. et al.)
Judges for the IoPP described the bottle as a breakthrough in the juice industry because it embodied “ . . . a distinctive shape, broad label panel and unique design to enhance shelf appeal and product quality.” The bottle also went on to win a WorldStar Award, which is considered the pre-eminent international award sponsored by the World Packaging Organisation in packaging and is only given to products that have won recognition in a national competition.
Although the aforementioned containers may function satisfactorily for their intended purposes, there remains a continuing need for a blow molded plastic container having vacuum panels, which enhance the structural integrity of the container while requiring a minimum use of plastic. Also, these vacuum panels need to be aesthetically pleasing and be capable of being manufactured in conventional high-speed equipment.